1. Field of the Invention
The invention relates to the field of exercising machines, and in particular to exercising machines simulating a stepping or climbing action in which the rate of energy input into the exercise machine, or more generally the power output of the human exerciser, is monitored and the load of the exercising machine controlled to maintain power input into the machine or power output from the human exerciser more accurately monitored.
2. Description of the Prior Art
Stepping exercise machines are well known to the art and have been built with a large number of designs and control methodologies. Typical examples of prior art stair climbing or stepping exercise machines can be found in Robards, Jr. et al., "Exercise Apparatus for Simulating Stair Climbing," U.S. Pat. No. 5,135,447 (1992); Hennessey et al., "Exercise Machine and Transmission Therefor," U.S. Pat. No. 5,139,469 (1992); Bull, "Exercise Apparatus, " U.S. Pat. No. 5,013,031 (1991); Stark et al., "Exercise Apparatus Having High Durability Mechanism for User Energy Transmission," U.S. Pat. No. 4,949,993 (1990); and Potts, "Stair Climbing Exercise Apparatus," U.S. Pat. No. 4,708,338 (1987). The type of mechanical linkages and arrangements to provide the stair climbing action, the types of load devices as well as how those loads are controlled varies considerably over the art and different examples can be found in each of these references.
For example, in Sweeney, Jr., "Program Exerciser Apparatus and Method," U.S. Pat. No. 4,358,105 (1982), a stepper is described which uses a pony brake as a load in combination with a flywheel in which the speed of the flywheel is controlled by a computer. In such devices, the energy rate or power of the exerciser, or at least the power input into the exercise machine by the human exerciser, varies considerably, not only over the course of a given exercise session, but dramatically between one exerciser and the next for the same speed control setting.
Such stepper machines usually include various handrails to allow the exerciser to steady himself or herself on the machine while exercising. It is almost a universal characteristic that exercisers will tend to lean on or support themselves in part on these handrails to effectively lighten or offset their weight on the stepping pedals and hence to decrease the amount of work that they put into the machine at a given speed setting.
Furthermore, the amount of energy expended by a petite 98-pound girl operating at a given speed, for example 20 steps per minute, is substantially different than the same amount of energy input into the machine by a 285-pound male linebacker also exercising at the rate of 20 steps per minute.
In addition, it must be kept in mind that in terms of health and exercise physiology, the important parameter is not the energy which is input into the machine, but rather the energy which the human user actually expends during the exercise. Only a small fraction of the energy burned in the human body ends up in measurable energy input into the exercise machine. By far, the greater amount of energy or calories burned is lost to sweat, body heat radiation and respiration.
Therefore, what is need is some type of a stepping or exercising machine and method for controlling the exercising machine whereby true, quantitative values of power input into the machine can be monitored and the machine load controlled to maintain those power levels substantially constant, and also to control the machine load relative to actual body power consumption during exercise.